Stars of the comedy sequel, including Bradley Cooper and Zach Galifianakis, descended on Grauman's Chinese Theatre in Los Angeles for the grand unveiling of the film on Thursday evening (19May11).

They were joined by primate Crystal, who has a role in the movie - and she appeared to be loving the attention, leaping up and down, playing with actress Kristen Bell's hair, and 'smiling' for photographers.

But officials at People for the Ethical Treatment of Animals (PETA) have blasted the stunt, insisting it was cruel to use the monkey in the film in the first place.

A PETA spokeswoman tells WENN, "We're not surprised to see that this monkey was subjected to the stressful conditions of a film premiere. The filmmakers have made it clear that they care little for her welfare, since they even banished the American Humane Association (which looks for only egregious cruelty during the actual filming) from the set during production.

"While Hollywood in general is becoming more aware that wild animals are mistreated behind the scenes and trained through physical abuse, (director) Todd Phillips ignores the evidence and continues to exploit these vulnerable creatures in his films just for cheap laughs."